Major advances in the design of potential vaccines and therapies will require a more complete understanding of HIV pathogenesis. Viral and host genes and gene products that impact the consequence of HIV infection need to be identified. Defining the location, load and genotype of HIV and deciphering the immune response to HIV at different stages of infection are also important. In contrast to other AIDS-related meetings planned for the coming year, this symposium will focus on HIV pathogenesis. All aspects of HIV replication and the host response to HIV will be covered. The meeting will include sessions on acute HIV/SIV infection, tropism, phenotypic, genetic and immunologic variation, the role of regulatory genes in pathogenesis, humoral and cellular responses to HIV/SIV, mechanisms of HIV/SIV transmission, and possible mechanisms of T cell depletion. Research on SIV will be included where comparable information on HIV is lacking. This is a particularly exciting time to focus attention on HIV pathogenesis, given the emerging body of somewhat controversial information on viral load, the role of dendritic cells in transmission, the significance of genetic variation, the uncertain role of mucosal immunity, the relevance of cytokine regulation of HIV production, and the indeterminant roles of autoimmunity, superantigens, and apoptosis in the decline of CD4+ T cell number. We hope this meeting will define the frontiers in HIV pathogenesis so that new insights relevant to the design of improved vaccines and therapeutics will emerge. Researchers in the areas of vaccine and drug development as well as aficionados of HIV pathogenesis should find this meeting interesting and stimulating.